Hey Everyone,
Iíve been building a new wheeled robot and I need help finding a good place to buy quality, high torque, low rpm 12V motors. Ideally, I would like to be able to buy wheels from the same place but thatís not a deal breaker.

I've used cordless screw drivers before to drive lawnmower wheels... And I've run them at 12V but not for very long :-) ... They should be ok at 6V which is the minimum motor supply voltage for the HB25.

Note: You might need to disable the locking mechanism of the cordless screw driver... I haven't done this in awhile, but it's as trivial as removing a single pin.

Alternatively you can look into windshield wiper motors... essentially that's all the motor mechanism is in the Motor Mount and Wheel Kit

If you don't mind blowing $50 on an idea. I don't know if you can put a wheel on it but I have used electric winch before on an arm.. The kind you use for a truck that can be picked up at Walmart for about $50. They work on 12 volts and are strong and slow. It is very easy to make it go CW and CCW by bypassing a relay and a gear stopper. I have used it to lift 100 lb. bags and the bags stay even when the power is off. I don't think you will find anything that gear down and cheap.

Al

Originally Posted by vanmunch

Hey Everyone,
I’ve been building a new wheeled robot and I need help finding a good place to buy quality, high torque, low rpm 12V motors. Ideally, I would like to be able to buy wheels from the same place but that’s not a deal breaker.

Hi Guys,
Thanks for the good advice and ideas. Iíve been looking some more at used power chairs and comparing them what it would take to find wheels, wheel mounts, ect. for a custom 12v system and not too surprisingÖ itís a lot cheaper to just buy a used power chair and use a Sabertooth 2X60 motor controller. Iíll let you know how the project goes, it should be done by mid June.

Keep an eye on your local Craigslist ads. You can sometimes score a great deal on one that isn't working well because of old batteries. If the peak loads end up exceeding the Sabertooth controller you may also want to look into the larger OSMC controllers. I have those on a couple large robots and they work well.

Allelectronics.com. I was in LA for many years, they have a variety of scooter motors, windshield wiper motors etc. The windshield wiper motors are slow with a lot of torque, it would not be hard to add wheels.

Power chair motors are the best for this type of weight, but of course they are the most expensive of the bunch. You used to be able to find them for $50-75, then the combat robot folks discovered them and the going rate is more like $250. Each.

Motors for automotive applications are good sources of cheap and high torque, but do keep in mind the motors are intended for intermittant duty only. This is especially true of starter motors.

When you work with this much torque it's often a good idea to use a more "giving" power transmission between the motor and wheel. You can achieve just that with a nice V-belt arrangement, AND enjoy more torque and lower speed. Put a small pulley on the motor, and place a larger pulley on the inside of the wheel. (Obviously the pulley needs to be a smaller diameter than the wheel!)

You then only need to put the wheels on bearing shafts, which is cheaper than augmenting the output shaft of the motor in order to accommodate the weight. I would surmise you could keep the Parallax motor and wheel kit, and just devise (say) a 10:1 V-pulley system. Not counting frictional losses, you get 10X the torque (and /10 the speed). You can try keeping the 6" wheels that come with the kit, or go with some beefier pneumatic wheels from Harbor Freight.

Alternatively you can look into windshield wiper motors... essentially that's all the motor mechanism is in the Motor Mount and Wheel Kit

Beau,

I'm guessing you meant power window motors? I don't think the windshield wiper motors are as strong. Plus with windshield wiper motors, the robot would just go forwad and then back not making much progress. (Yes, I know they could be modified to just move forward (I was being funny (I often have to point this out when I make a joke)).)

Edit: I see T_Chap also referred to windshield wiper motors. Are they really windshield wiper motors or power window motors?

I mentioned windshield wiper motors, however, All has a lot of different motors, some with gears which are slow running and high torque. Search their site for "motor" and see a lot more. Some of these gear motors are really high torque.

I mentioned windshield wiper motors, however, All has a lot of different motors, some with gears which are slow running and high torque. Search their site for "motor" and see a lot more. Some of these gear motors are really high torque.

Thanks for the reply T_Chap. I don't think I have heard of windshield wiper motors being used in robotics before. I guess they do need a lot of torque to move snow and slush at the end of such a long arm.

I had thought the Parallax motor set, Beau linked to, used power window motors, not windshield wiper motors. This made me wonder if you had just referred to windshield wiper motors since Beau had.

Now I see windshield wiper motors are also a good choice for robot motors.

I'm still unclear about the Parallax motors. Are they windshield wiper motors or power window motors?

A few years ago I built a trike bot with two windshield wiper motors that American Science & Surplus was selling at the time. They were very powerful, and that bot had no trouble rolling through grass twice as tall as it was.

Windshield wiper (they're made for continuous duty, but as noted, not all are capable of reversing -- check first!)
Power window
Power seat
... way down the list...
Starter (not all can be reversed; consumes lots of current; definitely not for anything but short duty)

A couple of other options popular in surplus:
DC winch (for cars, runs at 12V)
Golf cart motors (most are for 24-36V, but can run okay at 12V at lower torque)
Old-school satellite dish positioners

This motor seems a good candidate. Have no idea what its duty is, and the "inch-pounds" spec looks a bit suspicious. Cheap enough to try, and AmSci does allow returns (AFAIK).